Dear useRs, I am sure this is a fairly simple problem, but I just cannot get my head around it.
I have a dataframe which contains several factor variables. I can use table() to tell me how many different combinations there are of these variables. What I should like to do is to add a column to my original dataframe which labels each row according to the unique combination of factors. E.g. in the simple example below I create a dataframe 'df' with 3 columns, the values of which take 0 or 1. I can then classify each row in the table and I find that I have 4 unique combinations of factors. I would now like to add a fourth column to df which labels each row according to whether it was unique combination 1,2,3 or 4: x1=c(rep(0:1,6)) x2=c(rep(c(1,1,0,0)6)) x3=c(rep(1,6),rep(0,6)) df=data.frame(x1,x2,x3) tabledf=as.data.frame(with(df, table(x1,x2,x3))) res=c(3,4,3,4,3,4,1,2,1,2,1,2) desired=data.frame(x1,x2,x3,res) df tabledf desired I realise that this is probably quite simple to do, I am just struggling to get my head around it! Help much appreciated in advance. Cheers, Simon -------------------------------- Simon O'Hanlon BSc, MSc Department of Infectious Disease Epidemiology Imperial College London St. Mary's Hospital London W2 1PG ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
